Propeller for fluid



Aug. 25', 1953 Filed May 10 1949 G. S. FABER PROPELLER FOR FLUID 6 Sheets-Sheet l g- 25, 1953 G. s. FABER 2,649,921

PROPELLER FOR FLUID Filed May 10, 1949 6 Sheets-Sheet 3 Aug. 25, 1953 G. s. FABER' 2,649,921

' PROPELLER FOR FLUIDY Filed May 10, 1949 I 6 Sheets-Sheets 4 Aug. 25, 1953 G. s. FABER 2,649,921

' PROPELLER FOR FLUID Filed May 10, 1949 a Sheets-Sheet 5 Aug. 25, 1953 s; FABER I 2,649,921

PROPELLER FOR FLUID- Filed May 10, 1949 s She ets-Sheet e [raven for: G220; E567;

Patented Aug. 25, 1953 UNITED STATES PATENT OFFICE PROPELLER FOR FLUID V r Guy S. Faber, Chicago, Ill. Application May 1 0, 1949, Serial No. 92,469

This invention relates to I propeller for propelling a fluid relatively forwardly. r

One of the features of this invention is the provision of an improvedpropeller for more efficiently propelling a fiuidysuch as air, in a relatively forward-direction toprovide a more uniform volume of fluid flow and a deeper fluid beam penetration; another feature'of the invention is the provision of such a propeller including a plurality of blades operably .attached. around a mounting member and an annular ring substantially concentric with the axis of rotation of the mounting member and blades and mounted for rotation with the blades, this ring being located at the'rear of the blades and preferablyadjacent the leading edges of the blade -and the rear surface of the ring being sloped inwardly and forwardly; still another feature: of the invention is the provision of sucha propeller wherein the blades are located substantially entirely beyond the periphery of the mounting'member and have their trailing edges approximately aligned with the mounting memberiand their leading edges spaced rearwardly thereof;'" another feature of the invention is the provision of such a propeller wherein said annular ring is located adjacent the innermost portions of the leading edges of the blades and the rear surfaceof the ring is curved inwardly and forwardly with the outer edge portion of. this curved surface being substantially radial; yet another feature of the invention is the provision of a propeller. having a plurality of blades operably attached I around a mounting member with each of the trailing edges of the blades having a convex portion of a relatively small radius at the outer end thereof, a concave portion located inwardly ofgtheoonvex portion and a second convex portion located inwardly. of the concave portion and adjacent the, inner end of said trailing edge with the second convex portion extending beyond a radial line passing through the extreme tip of the first convex portion; another feature of the invention. is the pro--' vision of such a propeller ,wherein'each leading edge has a convex portion at the-outer end thereof and a concave portion located inwardly of the convex portion, with the convex portion extend ing beyond a radial line passing through the outermost part of the concaveportion; a further feature of the invention isthe provision of such a propeller wherein the convex portion of the leading edge of a blade is located opposite the concave portion of the trailing edge-of the adjacent blade whenviewed from'thefront and the on av portion. t leading ed e is similarly 5 Claims. (or. -159) located opposite the second convex portion of the trailing edge; a still further feature of the invention is the provision of such a propeller wherein the leading edge of one blade is spaced from the adjacent trailing edge of the next blade when the blades are arranged at zero pitch; another feature of the invention is the provision of a propeller comprising a plurality of blades operably attached around a rotatable mounting member with the total number of blades being an. odd number a further feature of the invention is the provision of a propeller having a plurality of blades operably. attached around a rotatable mounting member with the propeller having a plurality of balancing members spaced around the propeller with each of the balancing members bein connected to the propeller through a relatively fragile portion to. permit ready removal of a balancing member to achieve balance in the propeller; another feature of this invention is the provision of an improved flexible mounting means for a propeller. Other features and advantages of theinvention Will become apparent from the following description when considered with the accompanying drawings. Of the drawmgs:

Fig. l. is a front elevational view of a propeller embodying the present invention.

Fig. 2 is a side elevational view of the propeller of Fig. 1 and showing a motor. for use in driving the propeller.

Fig. 3 is a fragmentary front elevational view of'a' portion of the propeller illustrating the relative areas of the'bl'ades and the spaces between adjacent blades.

Fig. 4 is a rear elevational view of the propeller of Figs. 1 and 2. v 7

Fig. 5 is a semi-diagrammatic side elevational view of a propeller embodying the invention.

Fig. 6 is a fragmentary side elevational view partially in section showing a second embodiment of the invention.

Fig. 7 is an elevational view of a stamped metal blank used in making a third embodiment of the invention. 1

Fig. 8 is a front elevation of a'propeller, partially broken away, constructed from the blank of Fig. 7.

Fig. 9is a rear elevational view partially broken away of the propeller of Fig. 8.

Fig. 10 is a side elevational view of the propeller of Figs. 8 and 9.

Fig. 11 is a fragmentary side elevational view partially in section showing another embodiment 3 of the invention and the preferred structure for attaching a propeller to a shaft.

Fig. 12 is a front elevational view partially broken away of the embodiment of ll.

Fig. 13 is a side elevation of the propeller of Fig. 12 and showing a motor for driving the propeller.

Fig. i l is a rear elevational view, partially broken away, of the embodiment of Fig. ll.

The propeller shown in Figs. 1 to l, inclusive, comprises arotatable mounting member 2E! in the form of a sheet metal disc, a plurality of blades 2i substantially equally spaced therearound and an annular rin 22 serving as a Venturi ring and spaced rearwardly of the mounting member 29 and adjacent the leading edges 2 Id of the blades. In the embodiment of Figs. 1 to 4 the mounting member disc 26 also serves as a spider for mounting the blades 2!. provided with outwardly extending arms 22b substantially equally spaced around the periphery of the mounting member. As shown in Fig. 4, these arms 261) are each of substantially L-shape with the short leg of the L being preferably integral with the mounting member and the long leg extending substantially parallel to the periphery of the mounting member. Each arm 2% lies in a single plane and may be bent to a desired angle with respect to the axis of rotation of the propeller. Each arm 2% is used for mounting a blade 2|. The blade may be attached to the arm by means of rivets 23, soldering or the like. Although the arms 26b are preferably integral with the mounting disc 20, they also may be attached by rivets and the like.

The annular Venturi ring 22, as shown in Fig. 2, is attached to the inner ends of the leading edges 2 la of the blades 2!. The annular Venturi ring 22 which is substantially concentric with the axis of rotation of the propeller, has an outer diameter that is preferably not substantially greater than the diameter of the mounting disc 20 and that is substantially concentric therewith. The ring may be attached to the blades 21 by means of rivets 24 or the like. The arms 2% are of sufiicient size to give rigidity to the blades 2i and the annular Venturi ring 22 also adds rigidity to the blades at the leading edges thereof. The blades 22 are inclined in the same direction with respect to. the axis of rotation of the propeller and are preferably arranged at substantially the same pitch. A motor 25 may be used for rotating the propeller. This motor is, preferably arranged behind the mounting disc 29 and within the annular ring 22. e

As shown in Fig. 3, the leading edge Zia of a blade is spaced from the trailing edge 2ib of the next blade. This total spacing, as indicated at 26, should be at least 10% of the total disc area. This spacing will, of course, depend upon the pitch of the blades. Even when the blades are arranged at zero pitch, however, the leading and trailing edges are spaced from each other a substantial distance over their entire lengths.

As shown diagrammatically in Fig. 5, each blade 2! is substantially planar over its entire length and width.

Each trailing edge 2lb is provided with a convex portion 2 is of a relatively small radius at the outer end thereof, a concave portion 2 Id located inwardly of the convex portion and a second convex portion 2le located inwardly of the concave portion 2 id. This second convex portion 2 le extends beyond a radial line passing through the extreme tip of the first convex portion 2lc. The

convex and concave portions 2lc, 2ld. and He blend smoothly into each adjacent portion to provide a smooth curve. The concave portion 2 Id has an average radius of curvature that is greater than the average radius of curvature of the convex portion 2 Id. The second convex portion 2 is has an average radius of curvature greater than the average radius of curvature of the concave o tion .Z Ea h of her rtions 2 Bi and 216 have gradually; decreasing radii of curvature when progressing'from the outer end to the inner end of each portion.

' Each leading edge 2m has a convex portion 2 if at the outer end thereof and a concave portion 2 lg located inwardly of the convex portion. The

-- convexportion 21f extends beyond a radial line This mounting member-2Q is passing through the outermost part of the concave portion 2lg. The convex and concave portions blend smoothly into each other to form a smooth curve. The average radius of the concave portion 21g is greater than the average radius of the convex portion Zlf. The radii of curvature of eachof the concave and convex portions Elf and 2 lg gradually decrease when progressing from the outer to theinner end of each portion.

When the blades are assembled, as shown in the drawings, the convex portion 2 if of the leading edge la is located opposite the concave portion Zid of the trailing. edge 2ib when the propeller is viewed from thefront. The concave portion 219 of the leading edge is similarly located opposite, the second convex portion 216 of the trailing edge.

As shown in Figs. 2 and 6, the rear surface 22a of the annular Venturi ring 22 is sloped inwardly and forwardly toward the mounting disc 26. This rear surface preferably has the outer edge porticn 22b arranged substantially radially.

When the propeller is in operation to propel a fluid, such as air, the fluid is drawn from the back of the propeller and propelled forwardly and around the mounting disc 20 by the blades. At the rear of the propeller the. suction is substantially constant over the" entire area of the propeller includingthat portion opposite the mounting disc The air isv directed to the blades through andover the rotating annular Venturi ring 22. When the propelled air leaves the blades it is in the form of an annular cylinder that is constantly expanding as it flows beyond the lades. The blades direct the air in a radially expanding helix whichincreases in pitch as the dis tance from the propeller becomes greater. At a certain distance from the. propeller this radially expanding helix of an increasing pitch is converted to straight flow. of air. I This distance will depend upon the size of thepropeller, the speed of rotation and other factors. in one embodiment, the propelled air produced no noticeable helical effect at a distance of v1O feet from the propeller.

The trailing tip of each blade formed by the convex portion 210 aids. in preventing vortexing of air at the edge of the blade and thus substantially prevents either radial outward flow of fluid, or flow beyond the blade edge in a backward direction.

-The outer tip :2 to also serves to reduce turbulence in the propelled fluid and thus materially reduces the noise associated'with ordinary propellers', such as ventilating fans. The receding trailing edge, indicated by the concave portion ZIdQreduces the velocity of the air discharge in this area s'o'that the discharge velocities will be substantially uniform overthe entire width of 5. the blade. The inner extended area,.indicated by the second convex portion 2 le, serves to compensate for the lesser lineal velocity of this .portion of the blade so that the velocity of air or other fluid contacted by this portion of the blade will be substantially equal to the velocity of the air on the outer portions of the blade. Thus the particular curvature of the trailing edge of .each blade shown and described. 'herein provides a substantially uniform velocity in the fluid, such as air, over substantially the entire blade area. This uniform velocity serves to reduce materially the friction losses and eddy currents created by the ordinary fluid propellers and produces a greater volume of flow for any given propeller. All these effects combine to create a propeller having a higher efficiency of operation and that is very quiet.

The leading edge 2 la of each blade is provided with a tip having an average radius of curvature appreciably greater than the average radius of curvature of the tip 2 I of the trailing edge. This leading edge tip, as indicated by the convex portion 2 If, serves to pick up fluid and start it flowing across the revolving blades. The trailing edge of one blade and the leading edge of the next blade cooperate with each other to propel the fluid at substantially uniform velocity as has been previously described.

Each blade is made substantially planar over its entire width and length. as indicated at Fig. 5. These planar blades serve to increase the emciency of the propeller still further and reduce the tendency toward forming eddy currents with their resulting noise. The planar blades also require less power than equivalent blades of curved shape. The rotating annular Venturi ring 22, which is preferably fixed to the leading edge of the blade, cooperates with the extending trailing tip Zlc to produce a centrifugal force effect directing the air outwardly against the blades. This rotating ring avoids the eddy currents which occur when a non-rotating ring is employed. The ring also serves to reduce further the noise in the propeller as it aids in guiding the air substantially uniformly in an outward direction against the full areas of the blades. The ring also directs the fluid over a motor 25 located within the ring and thus cools the motor so that it operates more efficiently. The rotating ring eliminates the necessity of providing guiding vanes for forcing air-outwardly against the blades and serves, in the preferred embodiment, as a blade support for giving greater rigidity to the blades. The rotating Venturi ring 22 cooperates with the mounting disc 20 to aid the centrifugal blower action in forcing air outwardly behind the disc and against the blades. This provides a positive outward pressure and the combination cooperates with the blades, particularly at the trailing'edges thereof, to avoid vortexing at the outer edges of the blades. This avoidance of vortexing reduces materially the noise, increases the efficiency of the propeller and reduces potential power losses. i f

The mounting disc 20, which is preferably made of slight cup-shape with the convex surface on the side opposite the blades 2|, is preferably of relatively large diameter as shown in the drawings. This mounting disc prevents the return of air at the center of the propeller when the propeller is operated. This. prevention is especially important when the propeller is operafe ing against a relatively highpressure, or static resistance, such as, when forcing air through a" I 22d and blades 22!.

ventilator. The mounting disc also results in a strong sturdy propeller which is of especial importance in high speed propellers. The combination of the disc and the blades having the particular shapes described herein also produces a very pleasing appearance.

The new propeller is extremely quiet without sacrificing eiiiciency. When used in cooling a space such as a room, the propeller provides a smooth flow of air in large volume. The area that is cooled is extremely, large as the air expands as it flows from the propeller. The propeller may be used ina desk fan as it delivers a large amount of air at relatively low velocity pressure and thus provides a cooling effect without creating excessively strong drafts. The spacing that is provided between the leading edge of one blade and the trailing edge of the next blade cooperates with the rotating Venturi ring to draw air or other fluid from the back of the propeller over its entire diameter. This arrangement and operation assures no loss in fluid attraction and provides a cooling fluid flow over the motor.

The propeller is preferably provided with a plurality of balancing members spaced around the propeller with each of these balancing members being connected to the propeller through a relatively fragile portion to permit ready removal of one or more balancing members in order to achieve balance in the propeller. As shown in Fig. 4, these balancing members comprise a small ortion of metal 21 connected to an arm 2% through a thin neck portion 21a. It is preferred that these portions -of metal be provided in clusters as shown. In the embodiment of Fig. 4, there are two of these portions provided at the extreme end of each arm 2%. In balancing the propeller, one or more of these portions 21 may be broken off at the neck portion 21a.

In order to rotate the propeller the center of the rotatable mounting disc 20 is provided with a hole in which is clamped or otherwise attached a shaft 28. This shaft may be directly connected to the motor shaft as shown in Fig. 2.

In the embodiment shown in Fig. 6, the motor 25 is located in front of the rotatable mounting member disc I 29. This disc, as shown, has a curvature opposite to that of the mounting disc 20.

In the embodiment shown in Figs. '7 to 10, inelusive, the propeller is of relatively small diameter and the mounting disc and blades are made in one piece. In Fig. 7 there is shown the blank for making the propeller. This blank is formed from a fiat sheet that is punched and sheared, as indicated, to makethe mounting disc Adjacent the inner end of each trailing edge of a blade there is provided a small portion of metal 227 which serves as a balancing member, as previously described. In constructing the propellerfrorn the blank shown in Fig. 7, the mounting disc is given a slight cup shape so as to have a. form similar to the disc 29 shown in the first embodiment and theblades 22! are bent back behind the disc 220 tothe de sired pitch. The leading edges of the blades are then attached as by riveting to an annular Venturi ring 222, as shown in Figs. 8, 9and 10. The Venturi ring 22 serves to support the leading edges of the blades and give rigidity to the entire structure. e

In the embodiment shown in Figs. 11 to 14, in-' clusive, the blades 32] are stampedindividually from a sheet of metal and have their trailing edges attached to the mounting member disc 320 by small rivets 29 or the like. The trailing edge of each disc near the inner end thereof is provided with a plurality of small portions 321 of metal serving as balancing members. The first portion is attached through a reduced neck portion 327a to the main body of the blade. The next portions are preferably attached through a reduced neck to the portion of metal preceding it as shown in Fig. 12. Although only two portions 327 of metal are shown, it is obvious that more than two or only one could be provided if desired. The leading edge of each blade is attached to an annular Venturi ring 22 by a rivet 30 or the like. The ring 22 serves to support the leading edges of the blades and to give rigidity to the entire assembly.

As shown in Fig. 11, the propeller is preferably mounted on the motor shaft by means of a resilient mounting. As shown, the mounting for the propeller comprises a tubular member 34 of relatively large diameter that may be attached directly to the shaft of the motor 25. This tubular member has an outer end sic of expanded diameter and has an outer surface of a contour substantially the same as the contour of the inner surface of the mounting disc 32G adjacent the center thereof. The mounting member 3% is provided with an axial threaded hole at the outer end thereof which is adapted to receive the threaded bolt end of a cap member 32. This cap member has an expanded head 32a of substantially the same diameter as that of the outer end am of the tubular member 3!. This expanded head 32a is provided with an annular recessed portion 32b at the inner surface thereof extending around the threaded portion of the cap member. This annular recessed portion 32b provides space for containing an outwardly turned flange 3201 around an opening in the mounting disc 328 through which the cap member 32 extends. Sheets 33 and 34 of rubber or other resilient material are provided on either side of the mounting disc 32! and are compressed between the tubular member 3! and the cap member 32.

In the new propeller it is preferred that an odd number of blades greater than one be provided. When a fan having an even number of blades is employed on alternating current, the alternating sine wave of the current sets up a synchronous resonance in the propeller. Although propellers having an even number of blades are satisfactory for direct current, when the blades total an odd number the propeller may be used on either direct or alternating current without being subject to this synchronous resonance.

Having described my invention in considerable detail as related to several embodiments of the same, it is my intention that the invention be not limited by these details but rather be construed broadly within its spirit and scope as set out in the accompanying claims.

I claim:

1. A propeller for prcpeling a fluid relatively forwardly comprising: a rotatable mounting member; a plurality of blades operably attached around and located radially beyond said mounting member and inclined in the same direction with respect to the axis of rotation of said mounting member; and an annular ring substantially concentric with said axis and mounted for rotation with said blades, said ring being located inwardly of but adjacent to the leading edges of said blades and having its rear surface sloped inwardly and forwardly toward the axis of rotation.

2. A propeller for propelling a fluid relatively forwardly comprising: a rotatable mounting member of relatively large diameter; a plurality of blades having their trailing edges attached to said mounting member and their leading edges spaced rearwardly thereof, said blades being lo cated radially beyond the mounting member and inclined in the same direction with respect to the axis of rotation of said mounting member; and an annular ring substantially concentric with said axis and mounted for rotation with said blades, said ring being located inwardly of but adjacent to the innermost portions of the leading edges of said blades, and the rear surface of said ring being sloped inwardly and forwardly toward the axis of rotation.

3. A propeller for propelling a fluid relatively forwardly, comprising: a rotatable mounting member of relatively large diameter; a plurality of blades having their trailing edges attached to said mounting member and their leading edges spaced rearwardly thereof, said blades being located radially beyond the mounting member and inclined in the same direction with respect to the axis of rotation of said mounting member and being located substantially entirely beyond the periphery of said mounting member; and an annular ring substantially concentric with said axis and mounted for rotation with said blades, said ring being located inwardly of the blades and attached to the innermost portions of the leading edges of said blades, and the rear surface of said ring being curved inwardly and forwardly toward the axis of rotation with the outer edge portion of said surface being substantially radial.

4:. A propeller for propelling a fluid relatively forwardly, comprising: a rotatable mounting member; a plurality of blades having leading and trailing edges and operably attached around said mounting member and inclined in the same direction with respect to the axis of rotation of said mounting member, each of said trailing edges having a convex portion of a relatively small radius at the outer end thereof, a concave portion located inwardly of said convex portion and a second convex portion located inwardly of said concave portion and adjacent the inner end of said trailing edge, said second convex portion extending beyond a radial line passing through the extreme tip of said first convex portion, each of said concave and convex portions blending smoothly into each adjacent portion, each of said leading edges having a convex portion at the outer end thereof and a concave portion located inwardly of said convex portion, said convex portion extending beyond a radial line passing through the outermost part of said concave portion, and said convex and concave portions forming asmooth curve on said leading edge, said convex portion of the leading edge being located opposite the concave portions of the trailing edge and having an average radius of curvature less than that of said concave portion and the concave portion of the leading edge being located opposite the second convex portion of the trailing edge and. having an average radius of curvature smaller than that of said convex portion.

5. A propeller for propelling a fluid relatively forwardly, comprising: a rotatable sheet metal mounting member disc; a plurality of blades located radially beyond the mounting member and having their trailing edges attached to said mounting member and their leading edges spaced 9 rearwardly thereof, said blades being inclined in the same direction with respect to the axis of rotation of said mounting member and being located substantially entirely beyond the periphcry of said mounting member; and an annular ring substantially concentric with said axis and mounted for rotation with said blades, said ring being located inwardly of but adjacent to the leading edges of said blades and having its rear surface sloped inwardly and forwardly, each of said trailing edges having a convex portion of a relatively small radius at the outer end thereof, a concave portion located inwardly of said convex portion and a second convex portion located inwardly of said concave portion and adjacent the inner end of said trailing edge, said second convex portion extending beyond a radial line passing through the extreme tip of said first convex portion, each of said concave and convex portions blending smoothly into each adjacent portion, each of said leading edges having a convex portion at the outer end thereof and a concave portion located inwardly of said convex portion, said convex portion extending beyond a radial line passing through the outermost part of said concave portion, and said convex and concave portions forming a smooth curve on said leading edge, said convex portion of the leading 10 edge being located opposite the concave portion of the trailing edge and having an average radius of curvature less than that of said concave portion, and the concave portion of the leading edge being located opposite the second convex portion of the trailing edge and having an average radius of curvature smaller than that of said convex portion.

GUY S. FABER.

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